In recent years, information processing devices and electronic business machines have been rapidly prevailing as a result of the development of an electronic technology.
As the prevailing of the electronic appliances, electromagnetic interference occurring in peripheral equipments as a result of influence of noises generated from electronic parts and troubles, such as malfunction, caused by static electricity are increasing and get into big problems.
In order to solve these problems, there is a demand for materials which are excellent in electrical conductivity (antistatic property) and in static-controlling properties.
Hitherto, electrically conductive polymeric materials containing polymeric materials having low electrical conductivity with which electrically conductive fillers, etc. are compounded have been widely used.
Metal fibers, metal powder, carbon black, carbon fibers, etc. are generally used as the conductive fillers. The use of metal fibers and metal powder as the conductive fillers, however, has a drawback because corrosion resistance is poor and satisfactory mechanical strengths are hardly obtainable, although an effect of imparting excellent electrical conductivity is attained.
When carbon black is used as the conductive filler, electrically conductive carbon blacks, such as Ketchen black, Vulcan XC72 and acetylene black which can provide high electrical conductivity even with a small amount, are used. These carbon blacks, however, have poor dispersibility in a resin.
Since the dispersibility of carbon black has an influence upon the electrical conductivity of the resin composition, special blending and mixing techniques are required in order to obtain stable conductivity.
When carbon fibers are used as the conductive fillers, the desired strength and modulus of elasticity can be obtained by using ordinary reinforcing carbon fibers. However, in order to impart electrical conductivity, it is necessary to use the fibers in a high concentration, resulting in a deterioration of the physical properties inherent to the resin.
Further, since localization of the conductive filler is unavoidable when a molded object having a complicated shape is to be prepared, variation of conductivity is caused and desired electrical conductivity is not obtainable.
In the case of carbon fibers, fibers having a smaller diameter is expected to be able to impart better electrical conductivity provided the added amount of the fibers is the same, because the contact area between the resin and the fibers increases.
Extremely fine carbon fibrils having excellent electrical conductivity are proposed (see, for example, Patent Document 1).
When the fibrils are mixed with a resin, however, the dispersibility thereof in the resin is so poor that surface appearance of a molded object is deteriorated and is not satisfactory.
When the resin is to be colored and when carbon black for use as an ordinary pigment is used as a colorant, it is necessary to use the carbon black in a large amount in order to develop a black color. This causes problems of dispersibility in the resin and surface appearance of a molded object.
A method for adding extremely fine carbon fibrils is known (see, for example, Patent Document 2). However, there is no mention of flame retardancy which is influenced by the fine carbon fibrils.
The disclosed method results in low flame retardancy and is not applicable to an article which is required to have high flame retardancy.
There is known a resin composition containing a thermoplastic resin and carbon nanotubes and compounded with at least one compound selected from phosphorus compounds, phenol compounds, epoxy compounds and sulfur compounds (see, for example Patent Document 3). In the working examples, there is only disclosed polycarbonate resin/acrylonitrile-butadiene-styrene resin. There are no working examples at all which disclose a combination a polycarbonate resin with a polyester resin derived from natural resources or a polylactic acid obtained from synthetic lactic acid.
When carbon nanotubes are compounded in a large amount so as to develop electrical conductivity, a case is occasionally caused in which appearance is deteriorated or impact strength is lowered. Further, there is no mention of an improvement in solvent resistance.
Hitherto, a polycarbonate resin/polyolefin resin alloy has low compatibility and low impact strength. A molded object of such an alloy is apt to cause layer delamination and has poor appearance. Thus, it is indispensable to improve the compatibility.    [Patent Document 1] Japanese Publication of Translation of PCT No. S62-500943    [Patent Document 2] Japanese Unexamined Patent Publication No. H03-74465    [Patent Document 3] Japanese Unexamined Patent Publication No. 2004-182842